1. Field of the Invention
The present invention relates generally to a standard memory data take in method, and is directed more particularly to a method of standard memory data take in which provides an efficient utilization of the memory area which is effective as a library for use with pattern recognition systems.
2. Description of the Prior Art
In the prior art of pattern recognition systems, there are the types that determine whether, for example, a subject pattern X to be judged belongs to group A' or not by using a photo-electric conversion device such as a television camera or the like. With such type of recognition systems, among the subject patterns that belong to the group A', a proper number of typical pattern data a1, a2, . . . are selected and then memorized. For the pattern data a certain threshold value is separately designated. When the difference between the data of the subject pattern X to be recognized and any one of the memory data a1, a2, . . . is found to be within the above threshold value, the subject pattern X is judged as the same pattern as an already established memory, in other words, judgement is made that it belongs to group A'.
One important matter for such pattern recognition systems of prior art lies in how effectively the memory area is used or not. In other words, since the area for memorizing the data is limited, the reliability of judgement is greatly influenced by the proper selection of samples whose data are adopted as standard memories and whether the threshold value upon the pattern recognition is adequately established or not. For instance, as shown on FIG. 1, when the distribution range of patterns in group A' has a shape as illustrated at A1 and the distribution of the pattern data a1, a2 . . . of group A' to be memorized is eccentrically located in relation with the shape A1 of the actual pattern distribution range shown on the same drawings, the ranges that are judged to "belong to group A'" by the memorized datas a1, a2, . . . and the threshold value (which in this case is illustrated by the radius at each point data a1, a2, . . . ) tend to become a narrower range than the true range.
In general practice, a number of samples that are known to belong to group A' and transported by a belt conveyer or the like as an example, are either taken in as memories by a process as illustrated on FIG. 2, or to be little more thorough by the human visual sight selection, an overall sampling to represent group A' is conducted and then memorized. However, when the number of samples that belong to group A' and are transported by a conveyer or the like are sequentially memorized, even though the samples are very similar to those already taken in as the standard memories, they are sequentailly taken in as standard memories. Further, even though it is desired that the samples to be memorized are sampled by human judgement, the human selection or judgement is not necessarily quantitative and is greatly influenced by the feeling at each time and a different sampling can be conducted by a different person, it therefore lacks in true reliability. As a result, closely similar patterns can be taken in as memory, such as illustrated as a1 and a2, a4 and a5 in FIG. 3, and it is often experienced that the memory area is not effectively used.
In order to overcome such defect, it is enough that a mass of pattern memory data may be taken in, but in actuality, the memory area is limited as above mentioned. Accordingly, in order to cover the distribution range of group A' with a limited memory area, it is necessary that the pattern memory data are selected suitably to sample the pattern data from the overall portion of the distribution range of group A'.